package commands

import (
	"fmt"
	"io"
	"os"
	"path/filepath"

	"github.com/spf13/cobra"

	"github.com/oam-dev/kubevela/apis/types"
)

const completionDesc = `Output shell completion code for the specified shell (bash or zsh). 
The shell code must be evaluated to provide interactive completion 
of vela commands.
`

const bashCompDesc = `Generate the autocompletion script for Vela for the bash shell.

To load completions in your current shell session:
$ source <(vela completion bash)

To load completions for every new session, execute once:
Linux:
  $ vela completion bash > /etc/bash_completion.d/vela
MacOS:
  $ vela completion bash > /usr/local/etc/bash_completion.d/vela
`

const zshCompDesc = `Generate the autocompletion script for Vela for the zsh shell.

To load completions in your current shell session:
$ source <(vela completion zsh)

To load completions for every new session, execute once:
$ vela completion zsh > "${fpath[1]}/_vela"
`

// NewCompletionCommand Output shell completion code for the specified shell (bash or zsh)
func NewCompletionCommand() *cobra.Command {
	cmd := &cobra.Command{
		Use:   "completion < bash | zsh >",
		Short: "Output shell completion code for the specified shell (bash or zsh)",
		Long:  completionDesc,
		Args:  nil,
		Annotations: map[string]string{
			types.TagCommandType: types.TypeSystem,
		},
	}

	bash := &cobra.Command{
		Use:                   "bash",
		Short:                 "generate autocompletions script for bash",
		Long:                  bashCompDesc,
		Args:                  nil,
		DisableFlagsInUseLine: true,
		RunE: func(cmd *cobra.Command, args []string) error {
			return runCompletionBash(os.Stdout, cmd)
		},
	}

	zsh := &cobra.Command{
		Use:                   "zsh",
		Short:                 "generate autocompletions script for zsh",
		Long:                  zshCompDesc,
		Args:                  nil,
		DisableFlagsInUseLine: true,
		RunE: func(cmd *cobra.Command, args []string) error {
			return runCompletionZsh(os.Stdout, cmd)
		},
	}

	cmd.AddCommand(bash, zsh)

	return cmd
}

func runCompletionBash(out io.Writer, cmd *cobra.Command) error {
	err := cmd.Root().GenBashCompletion(out)

	if binary := filepath.Base(os.Args[0]); binary != "vela" {
		renamedBinaryHook := `
# Hook the command used to generate the completion script
# to the vela completion function to handle the case where
# the user renamed the vela binary
if [[ $(type -t compopt) = "builtin" ]]; then
    complete -o default -F __start_vela %[1]s
else
    complete -o default -o nospace -F __start_vela %[1]s
fi
`
		_, err = fmt.Fprintf(out, renamedBinaryHook, binary)
		if err != nil {
			return err
		}
	}
	return err
}

func runCompletionZsh(out io.Writer, cmd *cobra.Command) error {
	zshInitialization := `#compdef vela

__vela_bash_source() {
	alias shopt=':'
	alias _expand=_bash_expand
	alias _complete=_bash_comp
	emulate -L sh
	setopt kshglob noshglob braceexpand
	source "$@"
}
__vela_type() {
	# -t is not supported by zsh
	if [ "$1" == "-t" ]; then
		shift
		# fake Bash 4 to disable "complete -o nospace". Instead
		# "compopt +-o nospace" is used in the code to toggle trailing
		# spaces. We don't support that, but leave trailing spaces on
		# all the time
		if [ "$1" = "__vela_compopt" ]; then
			echo builtin
			return 0
		fi
	fi
	type "$@"
}
__vela_compgen() {
	local completions w
	completions=( $(compgen "$@") ) || return $?
	# filter by given word as prefix
	while [[ "$1" = -* && "$1" != -- ]]; do
		shift
		shift
	done
	if [[ "$1" == -- ]]; then
		shift
	fi
	for w in "${completions[@]}"; do
		if [[ "${w}" = "$1"* ]]; then
			# Use printf instead of echo beause it is possible that
			# the value to print is -n, which would be interpreted
			# as a flag to echo
			printf "%s\n" "${w}"
		fi
	done
}
__vela_compopt() {
	true # don't do anything. Not supported by bashcompinit in zsh
}
__vela_ltrim_colon_completions()
{
	if [[ "$1" == *:* && "$COMP_WORDBREAKS" == *:* ]]; then
		# Remove colon-word prefix from COMPREPLY items
		local colon_word=${1%${1##*:}}
		local i=${#COMPREPLY[*]}
		while [[ $((--i)) -ge 0 ]]; do
			COMPREPLY[$i]=${COMPREPLY[$i]#"$colon_word"}
		done
	fi
}
__vela_get_comp_words_by_ref() {
	cur="${COMP_WORDS[COMP_CWORD]}"
	prev="${COMP_WORDS[${COMP_CWORD}-1]}"
	words=("${COMP_WORDS[@]}")
	cword=("${COMP_CWORD[@]}")
}
__vela_filedir() {
	local RET OLD_IFS w qw
	__debug "_filedir $@ cur=$cur"
	if [[ "$1" = \~* ]]; then
		# somehow does not work. Maybe, zsh does not call this at all
		eval echo "$1"
		return 0
	fi
	OLD_IFS="$IFS"
	IFS=$'\n'
	if [ "$1" = "-d" ]; then
		shift
		RET=( $(compgen -d) )
	else
		RET=( $(compgen -f) )
	fi
	IFS="$OLD_IFS"
	IFS="," __debug "RET=${RET[@]} len=${#RET[@]}"
	for w in ${RET[@]}; do
		if [[ ! "${w}" = "${cur}"* ]]; then
			continue
		fi
		if eval "[[ \"\${w}\" = *.$1 || -d \"\${w}\" ]]"; then
			qw="$(__vela_quote "${w}")"
			if [ -d "${w}" ]; then
				COMPREPLY+=("${qw}/")
			else
				COMPREPLY+=("${qw}")
			fi
		fi
	done
}
__vela_quote() {
	if [[ $1 == \'* || $1 == \"* ]]; then
		# Leave out first character
		printf %q "${1:1}"
	else
		printf %q "$1"
	fi
}
autoload -U +X bashcompinit && bashcompinit
# use word boundary patterns for BSD or GNU sed
LWORD='[[:<:]]'
RWORD='[[:>:]]'
if sed --help 2>&1 | grep -q 'GNU\|BusyBox'; then
	LWORD='\<'
	RWORD='\>'
fi
__vela_convert_bash_to_zsh() {
	sed \
	-e 's/declare -F/whence -w/' \
	-e 's/_get_comp_words_by_ref "\$@"/_get_comp_words_by_ref "\$*"/' \
	-e 's/local \([a-zA-Z0-9_]*\)=/local \1; \1=/' \
	-e 's/flags+=("\(--.*\)=")/flags+=("\1"); two_word_flags+=("\1")/' \
	-e 's/must_have_one_flag+=("\(--.*\)=")/must_have_one_flag+=("\1")/' \
	-e "s/${LWORD}_filedir${RWORD}/__vela_filedir/g" \
	-e "s/${LWORD}_get_comp_words_by_ref${RWORD}/__vela_get_comp_words_by_ref/g" \
	-e "s/${LWORD}__ltrim_colon_completions${RWORD}/__vela_ltrim_colon_completions/g" \
	-e "s/${LWORD}compgen${RWORD}/__vela_compgen/g" \
	-e "s/${LWORD}compopt${RWORD}/__vela_compopt/g" \
	-e "s/${LWORD}declare${RWORD}/builtin declare/g" \
	-e "s/\\\$(type${RWORD}/\$(__vela_type/g" \
	-e 's/aliashash\["\(.\{1,\}\)"\]/aliashash[\1]/g' \
	-e 's/FUNCNAME/funcstack/g' \
	<<'BASH_COMPLETION_EOF'
`
	_, err := out.Write([]byte(zshInitialization))
	if err != nil {
		return err
	}

	if err = runCompletionBash(out, cmd); err != nil {
		return err
	}

	zshTail := `
BASH_COMPLETION_EOF
}
__vela_bash_source <(__vela_convert_bash_to_zsh)
`
	_, err = out.Write([]byte(zshTail))
	return err
}
